Oscillation generation



Mai-ch 19, 1935. J N, wHlTAKER 1,995,164

OSCILLATION GENERATION Filed Oct. 19, 1955 2 I ,1 our/ ur MEET 22 g omulk INVENTOR JAMES N WHlTAKER ATTORNEY Patented Mar. 19, 1935 PATEOSOILLATION GENERATION James N. Whitaker, ,Tuckahoe, N. Y., assignor toRadio Corporation of America, a corporation of Delaware ApplicationOctober V i 5 Claims.

In my copending application Serial Number 599,946, filed March 19, 1932,I have disclosed an oscillation generator utilizing negative resistanceaction of a multi-electrode tube for producing 5 high frequencyoscillations and utilizing regenerative action between other electrodesof the same tube for producing frequency stabilizing oscillations. Mypresent invention presents an improvement thereover in that the poweroutput of the oscillations in the negative resistance portion of thesystem is materially enhanced.

According to my present invention, in order to increase the negativeresistance output of an electron discharge device, I connect together aplurality of the electrodes which otherwise would be subjected todifierent operating potentials. I have discovered that by so doing,there is an improved negative resistance or dynatron output even though,as far as I am aware, the tubes were not intended for negativeresistance action.

I shall describe my present invention more fully with the aid of theaccompanying drawing which is a wiring diagram of a circuitincorporating my latest contribution to the art.

In greater detail, the fundamental frequency controlling element of thesystem shown in the drawing is a piezo-electric crystal 2 which isconnected between the cathode 4 and the first grid, control, or coldelectrode 6 adjacent the cathode. For biasing purposes a choke coil 8 inseries with the grid leak condenser arrangement 10 is also connectedbetween the grid 6 and cathode 4.

The second and third grid electrodes 12, 14

10 are directly connected together by the connection 16, and betweenthem and the cathode there is connected a tunable circuit 18 tuned tothe fundamental frequency of the piezo-electric element 2. The gridelectrode 12 would normally be the screen grid and may be termed anintermediate grid. The grid 14 would normally be the suppressor grid ofthe tube 10 and would normally be adjacent the anode 20 of tube 10. Be-

tween the anode or plate 20 and the cathode there is connected a secondtunable circuit 22. The lower ends of the tuned circuits 18, 22 areconnected to ground for high frequency currents by the action ofby-passing condensers 24, 26. Plate 20 is maintained through lead 28 ata lower positive potential with respect to the cathode 4 than thecombined electrodes 12, 14 which are maintained at a higher positivepotential with respect to the cathode by the application of 2.voltagefrom potentiometer 30 through lead 32.

1933, Serial No. 694,225

Oscillations are set up in the tuned circuit- 18 by virtue ofregenerative action, feedback occurring through the interelectrodecapacity exist ing between the grid 6 and the grids 12, 14.

Oscillations at the same or preferably a harmonic frequency orsub-harmonic frequency, are set up in circuit 22 by virtue of negativeresistance or dynatron action as described more fully in my copendingapplication already referred to. I have found, by connecting the grids12, 14 together, that there is a substantial increase in power at theharmonic frequencies circuit 22, which of course should be tuned to thedesired harmonic of circuit 18 .or to the fundamental frequency of thecrystal 2. Moreover, if desired, circuit 22 may be tuned to the samefrequencyas the crystal 2 or to some sub-harmonic.

It is not necessary that the crystal be used, for

regenerative oscillator of the tuned grid, tuned plate type, feedbackoccurring as before by virtue of interelectrode capacity within thetube.

If a controlling frequency source is connected to the points XXindicated on the drawing, circuit 18 may be tuned to the same, toamultiple, or to 7 some sub-multiple of the controlling frequency, andsimilarly circuit 22 may be tuned to the same frequency as thecontrolling frequency applied to points X or to some harmonic thereof,or to some sub-harmonic thereof, it being understood further thatcircuits 18 and 22 may be tuned simul taneously to the same or differentfrequencies.

Also, it is to be clearly understood that my present invention isapplicable to many other circuits such as any one of those disclosed inmy copending application already referred to. Consequently, I do notintend to be limited by what I have illustrated in the drawing, but mypresent invention is to be, given the full width, scope and depthindicated by the appended claims.

Having thus described my invention, what I claim is: 1

1. An oscillation generating system comprising a tube having an anodeelectrode, a grid adjacent the anode, a cathode electrode, a gridadjacent the cathode and a grid intermediate said 2 the. grid adjacentthe cathode and the cathode, short circuiting means connecting directlytogether the intermediate grid and the grid adjacent the anode, anoscillatory circuit connected between the grids connected together andsaid cathode, and an oscillatory circuit connected between said anodeand cathode.

2. Apparatus as claimed in the preceding claim wherein said'anode ismaintained at a positive 10* terized by the fact that means are providedfor maintaining said anode at a lesser positive potential with respectto said cathode, and being further characterized by the fact that theoscillatory circuit connected'betweensaid anode and 7 said cathode istuned to a harmonic of the frequency of the oscillatory circuit betweenthe grid adjacent said cathode and said cathode.

4. An oscillation generator comprising a vacuum tube having an anode, acathode, a control grid, 2. screen grid and a suppressor grid, apiezo-electric crystal connected between the control grid and cathode,means short circuiting to gether said screen grid and said suppressorgrid, a tuned circuit connected between the grids connected together andsaid cathode, a tuned circuit connected between said anode and cathode,means for maintaining said anode at a positive potential with respect tosaid cathode, and means for maintaining suppressor and screen grids at ahigher positive potential with respect to said cathode.

5. Apparatus as claimed in the preceding claim characterized by the factthat the circuit connected between said anode and cathode is tuned to aharmonic of the operating frequency of said piezo-electric crystal.

JAMES N. WHITAKER.

